Understanding arsenic behavior in alluvial aquifers:Evidence from sediment geochemistry,solute chemistry and environmental isotopes

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外文摘要：The hydro-geochemistry and isotopic variations in groundwater,coupled with sediment geochemistry,were investigated in the Middle Gangetic Plain,India,to better understand the aquifer dynamics that influence the arsenic(As)evolution and mobilization.Eighty-four groundwater samples,thirteen River water samples,and two sediment cores(33 mbgl)were studied.The samples were analyzed for major ions and trace metals,including As and stable isotopic variability(δ2H,δ18O,and δ13C).The study area was categorized into older and younger alluvium based on existing geomorphological differences.Younger alluvium exhibits higher As enrichment in sediment and groundwater,ranging of 2.59-31.52 mg/kg and bdl to 0.62 mg/L.Groundwater samples were thermodynamically more stable with As(OH)3 species ranging from 88.5％to 91.4％and FeOOH from 69％to 81％,respectively.PHREEQC and mineralogical analysis suggested goethite and siderite act as a source and sink for As.However,statistical analysis suggested reductive dissolution as the primary mechanism for As mobilization in the study area.Spatio-temporal analysis revealed elevated concentrations of As in the central and northeastern regions of the study area.Stable isotope(δ2H and δ18O)analysis inferred active recharge conditions primarily dri-ven by precipitation.The depleted d-excess value and enriched δ18O in the groundwater of younger allu-vium indicate the effect of groundwater recharge with significant evaporation enrichment.Groundwater recharge potentially decreased the quantity of arsenic in groundwater,whereas evaporation enrichment increased it.Rainwater infiltration during recharge introduces oxygenated water into the aquifer,leading to changes in the redox conditions and facilitating biogeochemical reactions.The carbon isotope(δ13C)results suggest that high microbial activity in younger alluvium promotes As leaching from sediment into the groundwater.

外文关键词：

Groundwater rechargeReductive dissolutionOlder alluviumYounger alluviumGhazipurStable isotope

作者：

Shailesh Kumar Yadav、AL.Ramanathan、Chidambaram Sabarathinam、Alok Kumar、Manoj Kumar、Anshula Dhiman

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作者单位：

School of Environmental Sciences,Jawaharlal Nehru University,New Delhi 110067,India

Water Research Center,Kuwait Institute for Scientific Research,Kuwait

Department of Environmental Studies,University of Delhi,110007,India

Department of Earth and Environmental Sciences,Indian Institute of Science Education and Research Mohali,Sector 81,140306,India

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基金：

CSIR(Government of India)for offering the CSIR-SR FellowshipIUACMinistry of Earth Sciences(MoES)under the Geochronology projectCIF(Central Instrumentation Facility),School of Environmental SciencesAIRF(Advanced Instrumentation Research Facility),Jawaharlal Nehru University,New Delhi,IndiaCSIR fellowship

项目编号：

MoES/P.O.Seismic809-Geochron/2012

出版年：

2024

DOI：

10.1016/j.gsf.2024.101844

地学前缘(英文版)

中国地质大学（北京）北京大学

地学前缘(英文版)

CSTPCD

影响因子：0.576

ISSN：1674-9871

年,卷(期)：2024.15(5)